Silicon carbide crystal ingot processing method

Abstract

The invention provides a silicon carbide crystal ingot processing method. A first circle, a second circle and a connecting line are drawn on the first end face of the silicon carbide crystal ingot, then the first end face of the bottom support is fixed to the second circle of the first end face of the silicon carbide crystal ingot, the bottom support is fixed to a workbench of a wire cutting machine, and the axis of the bottom support is parallel to a diamond wire of the wire cutting machine; and cutting the silicon carbide crystal ingot along the connecting line through a wire cutting machine by adopting a preset cutting process until the intersection of the first circle and the connecting line, finally cutting the silicon carbide crystal ingot along the edge of the first circle through the wire cutting machine by adopting a preset circle cutting process, and separating the silicon carbide crystal ingot from the bottom support. According to the method, the silicon carbide crystal ingot is cut along the connecting line through the preset cutting process until the first circle intersects with the connecting line, and then the silicon carbide crystal ingot is cut along the edge of the first circle through the preset circle cutting process, so that the edge material of the silicon carbide crystal ingot can be rapidly removed, and the machining precision can be effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of crystal processing, specifically to a method for processing silicon carbide ingots. Background Technology

[0002] Silicon carbide (SiC), as a third-generation semiconductor material, possesses high hardness, high breakdown electric field capability, high thermal conductivity, and electron saturation velocity, and is widely used in power devices, radio frequency devices, and other fields. Silicon carbide ingots are typically grown using the physical vapor transport method. They have a relatively large initial diameter, and certain defects at the edges do not meet the requirements of subsequent wafer processing. Therefore, it is necessary to reduce the ingot diameter to the target size and remove the edge defects.

[0003] Currently, the industry mainly relies on grinding to process the diameter of silicon carbide ingots. This involves using a precision grinding machine with a diamond wheel or grinding disc to mechanically grind the edges of the ingot, gradually removing edge material to the target diameter.

[0004] However, due to the high hardness of silicon carbide, the single cutting depth is small when using grinding methods. If a large amount of edge material needs to be removed, it takes a lot of time, resulting in low processing efficiency of silicon carbide ingots. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a silicon carbide ingot processing method to solve the problem of low efficiency in removing edge material using existing grinding processing methods.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] A method for processing silicon carbide ingots, comprising:

[0008] S10. Draw a first circle, a second circle, and a connecting line on the first end face of the silicon carbide ingot. The silicon carbide ingot is a standard cylindrical structure. The center of the first circle is the same as the center of the second circle, and the diameter of the first circle is larger than the diameter of the second circle. One end of the connecting line is connected to the center of the first circle, and the other end extends to the edge of the first end face of the silicon carbide ingot.

[0009] S20. Fix the first end face of the base to the second circle of the first end face of the silicon carbide crystal ingot, wherein the diameter of the first end face of the base is the same as the diameter of the second circle.

[0010] S30. Fix the base to the worktable of the wire EDM machine and make the axis of the base parallel to the diamond wire of the wire EDM machine.

[0011] S40. The wire cutting machine uses a preset cutting process to cut silicon carbide ingots along the connecting line until the first circle intersects with the connecting line. The preset process includes the total cutting amount of diamond wire, the linear speed of diamond wire, the cutting speed of diamond wire, and the wire tension of diamond wire.

[0012] The S50 wire EDM machine uses a preset circular cutting process to cut silicon carbide ingots along the edge of the first circle. The preset circular cutting process includes the rotation angle of the worktable, the rotation speed of the worktable, and the linear speed of the diamond wire.

[0013] S60. Separate the silicon carbide ingot from the base.

[0014] Preferably, in S10, it includes:

[0015] S101. Draw the first circle on the first end face of the silicon carbide ingot;

[0016] S102. Draw the second circle with the center of the first circle;

[0017] S103. Draw a parallel line on one side of the silicon carbide ingot that is parallel to the axis of the silicon carbide ingot and connected to the first end face of the silicon carbide ingot.

[0018] S104. Connect the first connecting line to the center of the first circle to form a connecting line.

[0019] Preferably, after S30 and before S40, it also includes:

[0020] S31. Adjust the height of the diamond wire and align it with the first connecting wire.

[0021] Preferably, S20 includes:

[0022] The first end face of the base is bonded to the second circle of the first end face of the silicon carbide crystal ingot.

[0023] Preferably, bonding the first end face of the base to the second circle of the first end face of the silicon carbide ingot includes:

[0024] The first end face of the base is bonded to the second circle of the first end face of the silicon carbide ingot using wax.

[0025] Preferably, S60 includes:

[0026] The bonding area between the silicon carbide ingot and the base is heated to separate the silicon carbide ingot from the base.

[0027] Preferably, the linear velocity of the diamond wire is in the range of 10 m / s to 25 m / s.

[0028] Preferably, the tension of the diamond wire is in the range of 10N to 50N.

[0029] Preferably, the rotation angle of the worktable is in the range of 360° to 370°.

[0030] Preferably, the rotational speed of the worktable is in the range of 0.01° / s to 0.1° / s.

[0031] Based on the above, the present invention provides a silicon carbide ingot processing method, in which a first circle, a second circle, and a connecting line are drawn on the first end face of the silicon carbide ingot. Then, the first end face of the base is fixed to the second circle on the first end face of the silicon carbide ingot. The base is then fixed to the worktable of the wire cutting machine, and the axis of the base is parallel to the diamond wire of the wire cutting machine. The silicon carbide ingot is then cut along the connecting line using a preset cutting process by the wire cutting machine until the first circle intersects with the connecting line. Finally, the silicon carbide ingot is cut along the edge of the first circle using a preset cutting circle process by the wire cutting machine, and then the silicon carbide ingot is separated from the base. The silicon carbide ingot processing method disclosed above first uses a preset cutting process to cut the silicon carbide ingot along the connecting line until the first circle intersects with the connecting line. Then, a preset cutting circle process is used to cut the silicon carbide ingot along the edge of the first circle. This not only quickly removes the edge material of the silicon carbide ingot, but also effectively ensures processing accuracy. Compared with the existing grinding processing method for silicon carbide ingots that remove more edge material, this application can effectively shorten the processing time and improve the processing efficiency. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0033] Figure 1 A flowchart of a silicon carbide ingot processing method provided in an embodiment of the present invention;

[0034] Figure 2 A flowchart illustrating the specific steps of drawing a first circle, a second circle, and connecting lines on the first end face of a silicon carbide ingot, provided in an embodiment of the present invention.

[0035] Figure 3 A flowchart of another silicon carbide ingot processing method provided in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram showing a first circle, a second circle, and a connecting line on the first end face of a silicon carbide ingot provided in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the structure of the base provided in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram showing the alignment of the connection line between the wire cutting machine and the silicon carbide ingot provided in an embodiment of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] This invention provides a method for processing silicon carbide ingots, see [link to relevant documentation]. Figure 1 and combined Figures 4 to 6 , Figure 1 This is a schematic flowchart of a silicon carbide ingot processing method, which includes the following steps:

[0042] S10. Draw a first circle O, a second circle O', and a connecting line L on the first end face of the silicon carbide ingot 1.

[0043] It should be noted that the silicon carbide ingot 1 of this application has a standard cylindrical structure. The first circle O is the required silicon carbide ingot 1. The center of the first circle O is the same as the center of the second circle O', and the diameter of the first circle O is larger than the diameter of the second circle O'. One end of the connecting line L is connected to the center of the first circle O, and the other end extends to the edge of the first end face of the silicon carbide ingot 1.

[0044] During the execution of step S10, refer to Figure 2 Step S10 specifically includes at least the following steps:

[0045] S101. Draw the first circle O on the first end face of the silicon carbide ingot 1.

[0046] S102. Draw the second circle O' with the center of the first circle O.

[0047] It should be noted that the first circle O in this application is the required silicon carbide ingot 1 portion. Therefore, it is necessary to first determine the required silicon carbide ingot 1 portion by drawing the first circle O, and then draw the second circle O' based on the center of the first circle O.

[0048] S103. Draw a parallel line L1 on one side of the silicon carbide ingot 1, which is parallel to the axis of the silicon carbide ingot 1 and connected to the first end face of the silicon carbide ingot 1.

[0049] It should be noted that a parallel line L1 is drawn on one side of the silicon carbide ingot 1, parallel to the axis of the silicon carbide ingot 1 and connected to the first end face of the silicon carbide ingot 1. This makes it easier for the diamond wire 3 to remain parallel to the axis of the silicon carbide ingot 1 when cutting the silicon carbide ingot 1 with diamond wire 3, thus avoiding excessive cutting of the diamond wire 3.

[0050] S104. Connect the first connecting line L to the center of the first circle O to form the connecting line L.

[0051] It should be noted that connecting the first connecting line L to the center of the first circle O forms the connecting line L. When cutting the silicon carbide ingot 1, it not only makes it convenient for the staff to observe the cutting amount, but also makes it convenient to measure the total cutting amount of the diamond wire 3. The total cutting amount of the diamond wire 3 is the distance from the intersection of the connecting line L and the first circle O to the edge of the silicon carbide ingot 1.

[0052] S20. Fix the first end face of the base 2 to the second circle O' of the first end face of the silicon carbide ingot 1.

[0053] It should be noted that the diameter of the first end face of the base 2 in this application is the same as the diameter of the second circle O'.

[0054] It is worth noting that the second end face of the base 2 is provided with a clamping part for clamping the worktable of the wire cutting machine.

[0055] S30. Fix the base 2 to the worktable of the wire EDM machine, and make the axis of the base 2 parallel to the diamond wire 3 of the wire EDM machine.

[0056] S40. The wire cutting machine uses a preset cutting process to cut the silicon carbide ingot 1 along the connecting line L until the first circle O intersects with the connecting line L.

[0057] It should be noted that the preset process includes the total cutting depth of the diamond wire 3, the linear speed of the diamond wire 3, the cutting speed of the diamond wire 3, and the tension of the diamond wire 3.

[0058] Specifically, the linear velocity of diamond wire 3 ranges from 10 m / s to 25 m / s.

[0059] It should be noted that the linear velocity of the diamond wire 3 in this application can be 10 m / s, 12 m / s, or 25 m / s, and those skilled in the art can choose according to their needs.

[0060] Specifically, the cutting speed of the diamond wire 3 is less than 2 mm / min.

[0061] It should be noted that the cutting speed of the diamond wire 3 in this application can be 1 mm / min or 1.5 mm / min, and those skilled in the art can choose according to their needs.

[0062] Specifically, the tension of the diamond wire 3 ranges from 10N to 50N.

[0063] It should be noted that the tension of the diamond wire 3 can be 10N, 50N, or 26N, and those skilled in the art can choose according to their needs.

[0064] The S50 wire EDM machine uses a preset circular cutting process to cut silicon carbide ingot 1 along the edge of the first circle O.

[0065] It should be noted that the preset circular cutting process includes the rotation angle of the worktable, the rotation speed of the worktable, and the linear speed of the diamond wire 3.

[0066] This application fixes the base 2 to the worktable of the wire EDM machine and makes the axis of the base 2 parallel to the diamond wire 3 of the wire EDM machine. When the diamond wire 3 cuts the silicon carbide ingot 1 along the connecting line L, it can ensure that the cutting amount at both ends of the silicon carbide ingot 1 is the same, thus achieving precise removal of the edge material of the silicon carbide ingot 1.

[0067] Specifically, the rotation angle of the worktable ranges from 360° to 370°.

[0068] It should be noted that the rotation angle of the worktable can be 360°, 370°, or 365°, and those skilled in the art can choose according to their needs.

[0069] Specifically, the rotational speed of the worktable ranges from 0.01° / s to 0.1° / s.

[0070] It should be noted that the rotation speed of the worktable can be 0.01° / s, 0.05° / s, or 0.1° / s, and those skilled in the art can choose according to their needs.

[0071] Specifically, the linear velocity of diamond wire 3 ranges from 10 m / s to 25 m / s.

[0072] It should be noted that the linear velocity of the diamond wire 3 in this application can be 10 m / s, 12 m / s, or 25 m / s, and those skilled in the art can choose according to their needs.

[0073] S60. Separate the silicon carbide ingot 1 from the base 2.

[0074] In this embodiment of the invention, a first circle O, a second circle O', and a connecting line L are first drawn on the first end face of the silicon carbide ingot 1. Then, the first end face of the base 2 is fixed to the second circle O' on the first end face of the silicon carbide ingot 1. The base 2 is then fixed to the worktable of the wire cutting machine, and the axis of the base 2 is parallel to the diamond wire 3 of the wire cutting machine. The silicon carbide ingot 1 is then cut along the connecting line L using a preset cutting process by the wire cutting machine until the first circle O intersects with the connecting line L. Finally, the silicon carbide ingot 1 is cut along the edge of the first circle O using a preset cutting process by the wire cutting machine, and then the silicon carbide ingot 1 is separated from the base 2. The silicon carbide ingot processing method disclosed above first uses a preset cutting process to cut the silicon carbide ingot 1 along the connecting line L until the first circle O intersects with the connecting line L. Then, a preset cutting circle process is used to cut the silicon carbide ingot 1 along the edge of the first circle O. This not only quickly removes the edge material of the silicon carbide ingot 1, but also effectively ensures the processing accuracy. Compared with the existing grinding processing method that removes more edge material from the silicon carbide ingot 1, this application can effectively shorten the processing time and improve the processing efficiency.

[0075] For details, please refer to Figure 3 After performing step S30 and before performing step S40, the following steps are also included:

[0076] S31. Adjust the height of the diamond wire 3 and align it with the first connecting wire L.

[0077] It should be noted that by adjusting the height of the diamond wire 3 to align and contact with the first connecting line L, the total cutting depth of the diamond wire 3 can be obtained by calculating the distance from the intersection of the connecting line L and the first circle O to the edge of the silicon carbide ingot 1. By inputting the total cutting depth into the cutting machine, the wire cutting machine can accurately cut the silicon carbide ingot 1 along the connecting line L using the preset cutting process.

[0078] Specifically, the steps in step S20 are as follows:

[0079] The first end face of the base 2 is bonded to the second circle O' of the first end face of the silicon carbide ingot 1.

[0080] It should be noted that the first end face of the base 2 can be fixed to the second circle O' of the first end face of the silicon carbide crystal ingot 1 by adhesive bonding or by vacuum adsorption by suction cup. Those skilled in the art can choose according to their needs. However, in this application, the first end face of the base 2 can preferably be fixed to the second circle O' of the first end face of the silicon carbide crystal ingot 1 by adhesive bonding.

[0081] Furthermore, the first end face of the base 2 is bonded to the second circle O' of the first end face of the silicon carbide ingot 1, including:

[0082] The first end face of the base 2 is bonded to the second circle O' of the first end face of the silicon carbide ingot 1 using wax.

[0083] It should be noted that the first end face of the base 2 can be bonded to the second circle O' of the first end face of the silicon carbide crystal ingot 1 with wax, or it can be bonded to the silicon carbide crystal ingot 1 with other materials. Those skilled in the art can make conventional replacements according to their needs.

[0084] It should also be noted that in the process of bonding the first end face of the base 2 to the second circle O' of the first end face of the silicon carbide crystal ingot 1 with wax, the silicon carbide crystal ingot 1 and the base 2 can be placed on a heating platform and heated (temperature 100±20℃, heating time greater than 5 minutes). Then, the wax stick is evenly applied to the bonding surface (first end face) of the silicon carbide crystal ingot 1 and the bonding surface (first end face) of the base 2. The bonding surface (first end face) of the silicon carbide crystal ingot 1 and the bonding surface (first end face) of the base 2 are then brought into contact, and the first end face of the base 2 is positioned at the second circle O' of the first end face of the silicon carbide crystal ingot 1 (i.e., the edge of the first end face of the base 2 coincides with the second circle O' of the first end face of the silicon carbide crystal ingot 1). After pressing for a period of time, the wax is allowed to cool and solidify by standing, thus achieving the bonding between the base 2 and the silicon carbide crystal ingot 1.

[0085] Specifically, during step S60, the specific execution steps include:

[0086] The bonding area between the silicon carbide ingot 1 and the base 2 is heated to separate the silicon carbide ingot 1 from the base 2.

[0087] It should be noted that by heating the bonding area between the silicon carbide ingot 1 and the base 2, the wax can be melted, thereby separating the silicon carbide ingot 1 from the base 2.

[0088] Preferably, after performing step S60, the method further includes:

[0089] Remove the wax from the bonding surface of the silicon carbide ingot 1 and the bonding surface of the base 2.

[0090] It should be noted that the wax on the bonding surface of the silicon carbide ingot 1 and the bonding surface of the base 2 can be removed with alcohol and kitchen paper, which can effectively prevent the wax from affecting the subsequent processing of the silicon carbide ingot 1 and the reuse of the base 2.

[0091] The beneficial effects of this application are:

[0092] 1. Significantly improves processing efficiency and quality when large-size crystal ingots require significant diameter reduction and removal.

[0093] Traditional cylindrical grinding machines use grinding wheels to remove material from the outer diameter of ingots. This process relies on the impact of abrasive grains on the wheel surface. If the cutting speed is high, this can easily lead to large-scale chipping, with dimensions exceeding 200μm. However, when using a diamond wire saw to cut the outer diameter, the uniform tension during the wire cutting process results in a relatively smooth edge profile, and the chipping size can be controlled below 30μm. This better ensures the integrity of the processed edge and improves the processing quality. Furthermore, when the material removal is large (>5mm), compared to the cutting speed of traditional grinding machines, wire sawing can significantly shorten the processing time and improve processing efficiency.

[0094] 2. Significantly reduces material waste, improves processing accuracy, and is both environmentally friendly and economical.

[0095] Traditional grinding requires material removal from the outer surface of an entire ingot, generating significant grinding force and heat. This necessitates the use of oil-based coolants, leading to environmental pollution and cleaning costs. Furthermore, wheel wear affects machining dimensions and accuracy, requiring frequent dressing and compensation. In contrast, diamond wire sawing results in minimal material loss, primarily affecting the kerf size (<1mm), significantly improving material utilization. It also uses water-based coolants, making it clean and environmentally friendly. Moreover, it allows for complex contour machining through program control, achieving micron-level precision. This represents a revolutionary improvement in machining accuracy and economic and environmental benefits.

[0096] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0097] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for processing silicon carbide ingots, characterized in that, include: S10. Draw a first circle, a second circle, and a connecting line on the first end face of the silicon carbide ingot. The silicon carbide ingot is a standard cylindrical structure. The center of the first circle is the same as the center of the second circle, and the diameter of the first circle is larger than the diameter of the second circle. One end of the connecting line is connected to the center of the first circle, and the other end extends to the edge of the first end face of the silicon carbide ingot. S20. Fix the first end face of the base to the second circle of the first end face of the silicon carbide ingot, wherein the diameter of the first end face of the base is the same as the diameter of the second circle; S30. Fix the base to the worktable of the wire cutting machine, and make the axis of the base parallel to the diamond wire of the wire cutting machine; S40. The wire cutting machine uses a preset cutting process to cut the silicon carbide ingot along the connecting line until the first circle intersects with the connecting line. The preset process includes the total cutting amount of the diamond wire, the linear speed of the diamond wire, the cutting speed of the diamond wire, and the wire tension of the diamond wire. S50. The wire cutting machine uses a preset circular cutting process to cut the silicon carbide ingot along the edge of the first circle. The preset circular cutting process includes the rotation angle of the worktable, the rotation speed of the worktable, and the linear speed of the diamond wire. S60. Separate the silicon carbide ingot from the base.

2. The silicon carbide ingot processing method according to claim 1, characterized in that, In S10, the following are included: S101. Draw the first circle on the first end face of the silicon carbide ingot; S102. Draw a second circle with the center of the first circle; S103. Draw a parallel line on one side of the silicon carbide ingot that is parallel to the axis of the silicon carbide ingot and connected to the first end face of the silicon carbide ingot. S104. Connect the first connecting line to the center of the first circle to form the connecting line.

3. The silicon carbide ingot processing method according to claim 2, characterized in that, After S30 and before S40, the following is also included: S31. Adjust the height of the diamond wire and align it with the first connecting wire.

4. The silicon carbide ingot processing method according to claim 1, characterized in that, S20 includes: The first end face of the base is bonded to the second circle of the first end face of the silicon carbide ingot.

5. The silicon carbide ingot processing method according to claim 4, characterized in that, The step of bonding the first end face of the base to the second circle of the first end face of the silicon carbide ingot includes: The first end face of the base is bonded to the second circle of the first end face of the silicon carbide ingot using wax.

6. The silicon carbide ingot processing method according to claim 5, characterized in that, The S60 includes: The bonding area between the silicon carbide ingot and the base is heated to separate the silicon carbide ingot from the base.

7. The silicon carbide ingot processing method according to claim 1, characterized in that, The linear velocity of the diamond wire ranges from 10 m / s to 25 m / s.

8. The silicon carbide ingot processing method according to claim 1, characterized in that, The tension of the diamond wire ranges from 10N to 50N.

9. The silicon carbide ingot processing method according to claim 1, characterized in that, The rotation angle range of the worktable is 360° to 370°.

10. The silicon carbide ingot processing method according to claim 1, characterized in that, The rotational speed of the worktable ranges from 0.01° / s to 0.1° / s.

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